The ever-decreasing service available to motorists at gas stations, the proliferation of self-service stations, and the economic advantage of the motorist changing his own oil at proper intervals has created a need for a convenient and economical oil level indicator on the automobile which is reliable and can be operated by the driver or owner of the vehicle at desired times. Such a device dispenses with the necessity for opening the hood of the vehicle and checking the oil level with the traditional dip stick, which can be a messy operation to say the least.
The above need has been recognized in prior U.S. Pat. No. 3,699,914 covering an oil level indicator for vehicles which is mounted on the instrument panel in ready reach of the driver. While functionally adequate, the patented indicator is quite complex in its structure and very impractical to manufacture on a mass production basis. It involves an assembly of metallic and plastic components, some of which require tedious and costly crimping opertions at the time of assembly. An excessive number of individual parts are utilized in the fabrication of the patented indicator and its assembling is tedious.
Accordingly, the primary object of this invention is to improve on the device in the above-noted prior patent by reducing substantially the number of parts, simplifying assembly procedure and costs, and utilizing molded plastics in the formation of all major components of the indicator. In this manner, the indicator according to the present invention is rendered much less costly to manufacture and assemble.
More particularly, it is an object of the invention to unite certain parts which are separately formed in the prior art and to mold these united parts from plastics. In the present device, a vacuum piston, its rod, and a yielding marginal piston seal are united and the piston is further constructed to serve as a seat for a piston return spring.
Another important and unique feature embodied in the present invention is an improved coupling between the bezel or face plate of the indicator and its piston cup or housing. This coupling eliminates the requirement in the prior art for crimping metal parts in assembled relationship with plastic or synthetic parts. Instead, the improved coupling comprises a snap type bayonet coupling between the face plate and piston cup of the indicator which is easy to operate and very secure.
Other features and advantages of the invention will appear during the course of the following detailed description.